1. Field of the Invention
The invention relates to a processing circuit, and more particularly to a processing circuit processing an external light.
2. Description of the Related Art
Liquid crystal displays (LCD) are widely used, as they possess the favorable advantages of thin profile, light weight, and low radiation. LCDs are frequently utilized in portable devices, such as mobile phones and personal digital assistants (PDA). Because LCDs do not emit light, a backlight, preferably capable of providing high, uniform brightness, is utilized to serve as a light source.
Generally, the portable devices comprise a battery to provide power. When LCDs are applied in the portable devices, the backlights will consume a large amount of the battery power. To reduce the power consumption, the conventional method adjusts the intensity of the light emitted from the backlight according to intensity of an external light. The conventional method detects the intensity of the external light and adjusts the intensity of the light emitted from the backlight according to the detection result.
However, the error rate of the detection result is increased when the illumination of the external light is high. FIG. 1 is a schematic diagram of an error rate of a conventional detection result. As shown in FIG. 1, when the illumination of the external light is higher than 800 lux, the error rate of the detection result may be −6% or 8%.